Surgical procedures for correcting, resecting or replacing joints are frequently performed in the medical field. One of the more commonly performed procedures pertains to corrective surgery of the hip joint. Specifically, the diagram of FIG. 1 illustrates the bones of a hip joint 10 including the pelvis 12 and a proximal end of the femur 14. The proximal end of the femur 14 includes a femoral head 16 disposed on a femoral neck 18. The femoral neck 18 connects the femoral head 16 to a femoral shaft 20. As shown in FIG. 2, the femoral head 16 fits into a concave socket in the pelvis 12 called the acetabulum 22, thereby forming the hip joint 10. The acetabulum 22 and femoral head 16 are both covered by articular cartilage that absorbs shock and promotes articulation of the joint 10.
Over time, the hip joint 10 may degenerate resulting in pain and diminished functionality. As a result, a hip replacement procedure, such as total hip arthroplasty or hip resurfacing, may be necessary. During hip replacement, a surgeon replaces portions of a patient's hip joint 10 with artificial components. In total hip arthroplasty, the surgeon removes the femoral head 16 and neck 18 and replaces the natural bone with a prosthetic femoral component 24 comprising a head 26, a neck 28 and a stem 30, as shown for example in FIG. 3. Alternatively, if the disease is confined to the natural acetabulum 22 of the pelvis 12, the surgeon resurfaces the acetabulum 22 using a reamer and replaces the natural surface with a prosthetic acetabular component including, for example, the hemispherical shaped cup 32 of FIG. 3 that may include a liner 34. To install the prosthetic cup 32, the surgeon connects the cup 32 to a distal end of an impactor tool or shaft and implants the cup 32 into the reamed acetabulum 22 by repeatedly striking a proximal end of the impactor shaft with a mallet. If the prosthetic cup 32 includes a liner 34, the surgeon snaps the liner 34 into the cup 32 after implanting the cup 32. Depending on the position in which the surgeon places the patient for surgery, the surgeon may use a straight or offset reamer to ream the acetabulum 22 and a straight or offset impactor to implant the prosthetic cup 32. For example, a surgeon that uses a postero-lateral approach may prefer straight reaming and impaction whereas a surgeon that uses an antero-lateral approach may prefer offset reaming and impaction.
A surgeon performing such procedures is met with a variety of difficulties due to the limited visibility and access to the diseased area. While reaming the acetabulum 22, the surgeon must be able to carefully monitor the trajectory of the reamer such that only the appropriate portions the acetabulum 22 are reamed according to plan. Likewise, during impaction of the prosthetic cup 32, as shown in FIG. 4, the surgeon must continuously monitor the trajectory as well as the depth of impaction D such that the cup 32 is adequately seated according to plan. Accordingly, surgeons may rely on computer-aided or robot-guided systems to help them more intuitively plan for the surgical procedures at hand. More specifically, computer-aided systems may enable the surgeons to graphically model the pathologic joint using medical images, such as computer tomography (CT) scans, and the like. Once a plan or model is generated, the surgeon may then view the model on a display screen in the operating room as guidance while performing the actual tasks. However, even with computer-aided and robot-guided systems, the surgeon may be unable to accurately monitor the actual trajectory and depth of the reamer or impactor. Moreover, the surgeon may be unable to accurately determine if the actual trajectory or depth is skewed from the original plan and if any corrections are needed to compensate for the skewed trajectory.
Accordingly, there is a need for improved systems or methods that further facilitate surgical procedures involving at least the hip joint. In particular, there is a need for a system or method that continuously provides the surgeon with more accurate and timely feedback regarding the trajectory as well as the depth of a reamer or a prosthetic cup, while still maintaining all of the benefits associated with computer-aided or robot-guided surgical systems. More specifically, there is a need for a system or method that is able to more readily compare the current progress of a surgical procedure with an original plan and offer corrective visual feedback for any detected diversion from the surgical plan.